The Void is a place between dimensions and between worlds.
To some it is known as the Outside, to others it is the Unknown. To most, however, it is called the Void. It is a timeless place inhabited by various seemingly intelligent entities who, for reasons beyond human understanding, have the desire to gain entrance to and vitiate the worlds outside their realm. These creatures are called "Voidborn". According to Vel'Koz, the Void is a very dark place, both he and Cho'Gath said that the daylight in Runeterra is too strong for them.
The lost city called Icathia seems to be connected to the Void, as some Voidborn are known to have appeared in the place and some mortals are known to have gained the Void's power in it. Mortals who encounter the power of the Void generally have one of two reactions:
- Like Malzahar, the Prophet of the Void, their minds may be overwhelmed and they may become willing servants to the dark apocalyptic destinies they see emanating from the Abyss. On Runeterra, these individuals are referred to as "The Cult of the Void".
- Like Kassadin, the Void Walker, they may be horrified and shocked into an unyielding desire to lay down their lives to forestall the doom they see. On Runeterra, these individuals are referred to as "The Preservers".
Some historical evidence show that, in times long past, there were massive magical projects throughout Runeterra oriented toward creating a bulwark against the Void. These projects and their history, however, remain apocryphal.
Currently, Malzahar performs rituals with his followers to sacrifice humans to the Void. In one instance Kassadin tried to stop him, however Malzahar managed to trick Kassadin into sending his daughter into the Void.
It is implied that living beings that enter the void are corrupted and transformed into voidborn creatures, as is the case with the Rift Herald.
Voidborn are shown to vary greatly in intelligence and development: Vel'Koz and Cho'Gath are highly intelligent (In due time Kha'Zix may aswell, but requires to assimilate other organic creatures.), while Kog'Maw is rather primitive (This may due to fact that he is an infant) and Rek'Sai is primeval and non-sapient, more akin to a wild animal. As such there are also different hierarchies, Rek'Sai for example is the queen of her kind and feared by the other Voidborn. Vel'Koz is likely in the higher hierarchy however, as he is allowed and able to execute other Voidborn should they become problematic for him.
All five known Voidborn seem to have a hunger that they must satisfy, and possess apostrophes in their names:
- Cho'Gath revels in fear and mayhem and depravity.
- Kha'Zix craves biological perfection.
- Kog'Maw simply wants food, albeit endlessly.
- Rek'Sai hunts those who cross her domain relentlessly.
- Vel'Koz seeks omniscience.
There currently exist two lesser Voidborn creatures who are summonable to the plane of Runeterra for a short time.
These lesser voidborn are both quadrupeds, with insectile legs that are similar in appearance. They are smaller in size in comparison to other voidborn, being around the size of a minion, implying that they may not be fully matured. It has been hinted that they are non-sapient, and possess no lead nor master; however, their demeanors can be (forcefully) lieged to those that summon them. These voidborn appear to be linked in some way to the champion who summoned them, being able to either increase their strength either directly from the summoners own strength ( Voidling) or defense ( Voidspawn).
There are multiple species of voidborn with only two being known: the Xer'Sai and the Zz'Rot. The Xer'Sai run rampant across the Sai Desert, a vast wasteland in southern Shurima, with their queen Rek'Sai being the apex predator of the entire region. The Zz'rot are diminutive quadrupeds with a volatile biology. They are also the only voidborn whose method of entry to Runeterra is known; their usage of portals. Presumably the remaining named voidborn: Cho'Gath, Kog'Maw, Kha'Zix, Vel'Koz and Baron Nashor are also members of individual species.
- Almost all the names given to the Voidborn are ancient Shuriman in origin. 
- While they are not Voidborn, Fizz, Illaoi, and Nocturne have a Void-themed skin.
- The Baron Nashor is also a creature from Void. 
- With the exception of Kha'Zix and Rek'Sai, it would seem that most of the Voidborns have (been forcibly) allied with Viktor and the Glorious Evolution, further enhancing their capabilities as evidenced by their Battlecast skins.
- It has been stated that there are possibly Void portals in Freljord which may mean that there are Void portals in other nations of Valoran, not just on Shurima.
- All Voidborn champions (except Kha'Zix) can deal true damage with their kits.
- All Voidborn champions (except Vel'Koz) have an ability that enhances their basic attacks in some way.
- Cho'Gath's Vorpal Spikes adds bonus magic damage to all his basic attacks to all units in front of him while toggled on, increaing the range the bigger he is.
- Kog'Maw's Bio-Arcane Barrage adds bonus damage equal to a percentage of the targets maximum health and increased attack range for 8 seconds.
- Kha'Zix's Unseen Threat adds magic damage on his basic attack. Kha'Zix's Taste Their Fear, if Evolved, increases basic attack range.
- Rek'Sai's Queen's Wrath adds bonus physical damage on her the next 3 basic attacks to her target and all surrounding enemies. Rek'Sai's Void Rush passively grants bonus attack speed.
- All champions that are Void-related stack something:
- Cho'Gath stacking health, attack range and model size with Feast
- Kassadin stacking the damage and mana cost of Riftwalk
- Kha'Zix stacking his usage of Void Assault
- Kog'Maw stacking the damage and mana cost of Living Artillery
- Malzahar stacking with his spell uses for Summon Voidling
- Rek'Sai stacking her Fury for Fury of the Xer'Sai and Furious Bite
- Vel'Koz stacking with his spell uses for Organic Deconstruction
- Related Themes
|Cho'Gath, the Terror of the Void||Birthplace|
|Kassadin, the Void Walker||Origin of Powers; wishes to stop the Void from spreading to Runeterra|
|Kha'Zix, the Voidreaver||Birthplace|
|Kog'Maw, the Mouth of the Abyss||Birthplace|
|Malzahar, the Prophet of the Void||Origin of Powers; works to bring the Void into Runeterra|
|Rek’Sai, the Void Burrower||Birthplace|
|Vel'Koz, the Eye of the Void||Birthplace|
|Geography of Runeterra|
|Valoran||Factions & Nations|
|Other Planes of Existance|
|Outside of Runeterra|